Many of them sucked, but almost all of them worked their asses off. A few of them were brilliant (the Butthole Surfers, IMSHO). I like some of MJ's music, but frankly I don't think he was a genius songwriter. Great performer, and had some nice hit songs.
I think something is gone with that era, in that now it's just the artist and his/her computer. No big setup, no 'control room', no tape assist punching in the vocals. No girlfriends snoring on the couch. And obviously, no band playing everything at once (that wasn't even really going on by the time I was working, though you did do things like bass/drums/guitar together with a rough vocal if it made sense for the song).
Like stained glass and the Saturn V, the art of making these kinds of records is going to be lost forever.